Why don't you simply sell your Doge at the best exchange,
grab the BTC, send it to Poloniex/C-Cex and then start buying?

I can't imagine anyone giving you a good deal by swapping out for Doge.

That sounds risky, and I suppose you want a great rate as well?

Better off playing the exchange game, and finding some clown
who wants to panic sell, because he didn't triple his money in
five hours. The longer you wait, the more you will pay ...